Method for starting water interception and water control of large-diameter earth pressure balance shield in ultra-deep water-rich soft rock stratum

Abstract

The invention discloses a method for starting water interception and water control of a large-diameter earth pressure balance shield in an ultra-deep water-rich soft rock stratum, and belongs to the technical field of shield construction. The tunnel portal adopts a multi-stage composite sealing system; the deep cracks are subjected to precise grouting reinforcement, and the precise grouting reinforcement comprises the reinforcement range, the hole arrangement mode, the grouting process, the grouting pipe construction, slurry, quality inspection and the hole sealing process; shield launching dynamic regulation and control; and whole-course monitoring and early warning. By means of the method, efficient and safe construction can be conducted on water conservancy tunnel engineering such as a shield with the diameter larger than or equal to 12 m, the burial depth larger than or equal to 60 m and medium weathered soft rock strata with bed rock fissure water development. And the water stopping effect during safe starting of the large-diameter shield in the ultra-deep, water-rich and soft rock stratum is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of shield construction, and particularly relates to a method for starting, cutting and controlling water of a large-diameter earth pressure balance shield in an ultra-deep water-rich soft rock stratum. BACKGROUND

[0002] Water conservancy flood control and drainage tunnels usually have the characteristics of large diameter, long distance and deep burial, and often need to pass through complex hydrogeological environments, especially ultra-deep water-rich soft rock strata near rivers and lakes. The soft rock stratum (such as strongly weathered rock, mudstone, shale, etc.) has low strength, is easy to soften and disintegrate when encountering water, has developed joint fissures, and has good water permeability.

[0003] Therefore, the current shield construction of water conservancy flood control and drainage tunnels mainly has the following problems: 1. Shield starting risk: Shield starting is a key risk point in tunnel construction. In the ultra-deep water-rich soft rock stratum, the main risks are high water pressure, large water gushing, and high pore water pressure due to deep burial. The development of soft rock fissures provides a good channel for groundwater. Once the portal is broken or the seal fails, a large amount of water and sand may suddenly gush out, causing the working well to be flooded, the ground to sink and collapse, and even the shield machine to be submerged.

[0004] 2. Stratum instability: The loss of underground water carries away fine particles, resulting in a decrease in effective stress of the stratum, softening and disintegration of soft rock, and triggering collapse of the soil around the front of the excavation face and the portal.

[0005] 3. Loss of control of shield posture: Water and sand gushing destroy the earth pressure balance of the excavation face, causing the shield machine to "knock its head" and lose control of its posture.

[0006] At the same time, the existing shield construction method has the following limitations: 1. Single dewatering: In ultra-deep, water-rich and fully replenished soft rock strata, conventional well-point dewatering is inefficient, costly, and difficult to lower the water level below the safety line. Large-scale pumping of underground water may cause serious ground subsidence and environmental problems.

[0007] 2. Conventional grouting reinforcement: Soft rock is broken and has strong connectivity of fissures. Conventional grouting grout is easily diluted and washed away by high-pressure water, making it difficult to form a uniform, complete and high-strength water stop curtain. The accuracy and effectiveness of deep grouting are difficult to control.

[0008] 3. Conventional portal sealing: Ordinary curtain rubber plates + folding pressure plates have insufficient sealing reliability under ultra-high water pressure and complex strata, and are easily broken by water gushing or damaged by sandstone abrasion.

[0009] 4. Challenge of large-diameter shield: When a large-diameter shield (usually diameter ≥ 6m) starts, the excavation area is large, the stratum disturbance range is wide, the pressure-bearing capacity and reliability of the portal sealing system are higher, and the water gushing risk is multiplied.

[0010] In summary, it can be known that the prior art has problems such as incomplete water stopping effect, poor reliability, high cost, large environmental disturbance and the like when coping with large-diameter shield safe launching in super-deep, water-rich and soft rock stratum, and cannot be used for construction of water conservancy tunnel projects such as a diameter ≥ 12 m shield, a buried depth ≥ 60 m and a fissure water developed in a medium weathered soft rock stratum.

[0011] Therefore, a safer, more efficient and controllable water stopping and controlling method is urgently needed to solve the industry problem of well flooding and stratum instability caused by high-pressure fissure water inflow during large-diameter shield launching in super-deep water-rich soft rock stratum. SUMMARY

[0012] The purpose of the present application is to provide a method for water stopping and controlling during large-diameter earth pressure balance shield launching in super-deep water-rich soft rock stratum, which is used for water conservancy tunnel projects such as a diameter ≥ 12 m shield, a buried depth ≥ 60 m and a fissure water developed in a medium weathered soft rock stratum (rock mass saturated compressive strength ≤ 15 MPa), and realizes a safer, more efficient and controllable water stopping and controlling method.

[0013] The purpose of the present application is realized by the following technical solutions: A method for water stopping and controlling during large-diameter earth pressure balance shield launching in super-deep water-rich soft rock stratum, comprising the following steps: S1: fine geological and hydrological modeling; S2: using a multi-stage composite sealing system for a tunnel portal; S3: using precise grouting reinforcement for deep fissures, wherein the step S3 comprises a reinforcement range, a hole arrangement mode, a grouting process, a grouting pipe structure, a slurry, quality inspection and a hole sealing process; S4: shield launching dynamic control; S5: whole-process monitoring and early warning, and starting emergency grouting when water inflow suddenly increases by more than 10% or settlement is greater than 5 mm / 24 h.

[0014] Further, the reinforcement range of the step S3 is 10 m above and below the shield tunneling range, and 1 D to the outside of the tunnel diameter D to the left and right, and the reinforcement length is +10 m of the shield main machine; The hole arrangement mode of the step S3 adopts a quincunx hole arrangement mode with a hole distance of 1.5 m x 1.5 m, and I-order holes to II-order holes are used for construction; The grouting process of the step S3 adopts a sectional construction, and grouting is performed every 1 m from bottom to top; The grouting pipe structure of the step S3 adopts a one-way valve pipe with a diameter of 40-60 mm, and 2-3 groups of jetting holes are arranged per meter of the one-way valve pipe; The slurry in step S3 adopts fast-setting multi-component slurry, and the water-cement ratio conversion adopts four-stage gradual thickening, and the water-cement ratios are 2:1, 1:1, 0.8:1 and 0.5:1 in turn; In step S3, the inspection holes for quality inspection are not less than 5%, and a 1.2Mpa water pressure test is carried out 3 days after grouting, wherein the water permeability of not less than 85% of the hole sections is not greater than 3Lu; In step S3, the hole sealing process adopts thick slurry with a water-cement ratio of 0.5:1, and simultaneously adopts 0.5Mpa pure pressure type hole sealing.

[0015] Further, step S1 comprises the following sub-steps: S11: Through TSP, borehole television and pumping test, the position, width and water conductivity of the fissure distribution within a range of 20m of the shield length are measured; S12: A three-dimensional hydrogeological model is established to predict the water gushing channel.

[0016] Further, step S2 comprises the following sub-steps: S21: A double-channel grouting pipe steel ring is pre-buried, and the pressure bearing of the grouting pipe steel ring is not less than 1.5 times the hydrostatic pressure; S22: A ring-shaped deep hole grouting curtain is arranged outside the portal; S23: A special sealing curtain and a triple hydraulic pressure plate are arranged at the portal, the special sealing curtain adopts 2-channel aramid fiber reinforced polyurethane curtain, and the pressure bearing of the special sealing curtain is not less than 1.0MPa.

[0017] Further, step S22 comprises: 3 rows of sleeve valve pipes are arranged in a ring shape outside the portal, the embedding hole depth of the sleeve valve pipes is not less than 5m from the aquiclude, and a super-fine cement-sodium silicate slurry solution is injected into the sleeve valve pipes to form a water stop body with a water permeability of k<10×-7 cm / s.

[0018] Further, in step S4, the diameter of the shield machine is not less than 12m, the starting depth is not less than 60m, the soil chamber pressure is 1.05-1.1 times the water-soil pressure, the rotation speed is not greater than 0.8rpm, and the speed is not greater than 5mm / min; the shield machine synchronous grouting adopts fast-setting double-liquid slurry, and the secondary grouting is carried out after the shield tail is removed by using polyurethane to seal the gap.

[0019] Further, the monitoring items of step S5 include the well water level, well water pressure, curtain compression force, ground surface settlement and seepage flow.

[0020] The beneficial effects of the present application are: 1) The water conservancy tunnel engineering of a diameter ≥12m shield, a buried depth ≥60m, and a medium-weathered soft rock stratum with fissure water development can be constructed efficiently and safely, and the water stopping effect is improved when a large-diameter shield is safely started in an ultra-deep, water-rich and soft rock stratum.

[0021] 2) Fracture water depth plugging: sequence plum blossom hole + splitting permeation grouting to make permeability ≤3Lu, overcome the uneven permeation problem of traditional process. 4h strength ≥20MPa, slurry shortens construction period by >30%.

[0022] 3) Triple waterproofing guarantee: deep grouting body (main waterproofing) + hole sealing (emergency water blocking) + simultaneous grouting (secondary sealing). BRIEF DESCRIPTION OF DRAWINGS

[0023] Fig. 1 For the plum blossom sequence hole arrangement plane in step S3 (I sequence hole→II sequence hole advancing direction); Fig. 2 For the deep fracture precise grouting range profile in step S3; In the figure, 1-I sequence hole, 2-II sequence hole, 3-reinforcement range, 4-shaft diaphragm wall enclosure structure, 5-origin shaft, 6-tunnel structure edge line. DETAILED DESCRIPTION

[0024] The technical solutions of the present application will be described below in conjunction with the embodiments, obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0025] Referring to Figs. 1-2 , the present application provides a technical solution: As Figs. 1-2 shown, a method for starting water blocking and control of large-diameter earth pressure balance shield in super-deep water-rich soft rock stratum can efficiently and safely construct water conservancy tunnel projects such as diameter ≥12m shield, buried depth ≥60m, and medium-weathered soft rock stratum with developed bedrock fracture water. Improve the water stopping effect when starting large-diameter shield in super-deep, water-rich, and soft rock stratum.

[0026] Specifically includes the following steps: S1: fine geology and hydrology modeling; Wherein step S1 includes sub-steps S11-S12, S11: Through TSP, borehole television and pumping test, the distribution of fractures within the range of shield length +20m is measured in terms of position, width and water conductivity; S12: Establish a three-dimensional hydrogeological model to predict water gushing channels.

[0027] Through the fine geology and hydrology modeling in step S1, the distribution of unfavorable geological structures such as faults, fracture zones and aquifers can be intuitively displayed, and combined with real-time monitoring data (such as surrounding rock deformation, earth pressure balance, etc.), the subsequent shield construction and safety warning are facilitated.

[0028] S2: The tunnel portal adopts a multi-stage composite sealing system; Step S2 includes the following sub-steps: S21: A double-channel grouting pipe steel ring is pre-buried, and the pressure bearing of the grouting pipe steel ring is not less than 1.5 times the hydrostatic pressure; S22: A ring-shaped deep hole grouting curtain is arranged outside the tunnel portal, and step S22 includes: three rows of sleeve valve pipes are arranged in a ring shape outside the tunnel portal, the buried hole depth of the sleeve valve pipe is not less than 5m from the aquiclude, and a super-fine cement-sodium silicate grout solution is injected into the sleeve valve pipe to form a water permeability k<10×-7cm / s water stop body.

[0029] S23: A special sealing curtain and a triple hydraulic press plate are arranged at the tunnel portal, the special sealing curtain adopts two aramid fiber reinforced polyurethane curtains, the pressure bearing of the special sealing curtain is not less than 1.0MPa, and the triple hydraulic press plate has a pressing force of 500kN / m.

[0030] Through the above technical solution, the double-channel grouting pipe steel ring and the arranged ring-shaped deep hole grouting curtain can effectively block the inflow of underground water and ensure the stability of the soil. The triple hydraulic press plate drives the special sealing curtain to expand outward through pressure, and cooperates with the rigid support of the turning plate to continuously press the shield body or segment under the mud pressure, so as to realize full sealing. At the same time, the special sealing curtain adopts two aramid fiber reinforced polyurethane curtains to tightly fit the gap between the shield machine shell and the tunnel portal through high-elasticity material, so as to prevent the inflow of mud and underground water from the annular gap. S3: Precise grouting reinforcement is adopted for deep fissures, and the step S3 includes a reinforcement range, a hole arrangement mode, a grouting process, a grouting pipe structure, a grout, a quality inspection and a hole sealing process; The reinforcement range of step S3 is 10m above and below the tunneling range of the shield, and 10m left and right of the outer diameter D of the tunnel, and the reinforcement length is +10m of the shield main machine. The hole arrangement mode of step S3 adopts a quincunx hole arrangement mode with a hole distance of 1.5m×1.5m, and the construction is performed from I-order holes to II-order holes. Specifically, as shown in the plan view of Fig. 1 A shaft diaphragm wall enclosure structure 4 is arranged outside the starting shaft 5, the reinforcement range 3 is outside the tunnel structure boundary line 6, the reinforcement range 3 is from +10m of the tunnel top to -10m of the tunnel bottom, 10m left and right of the outer diameter D of the tunnel, and the length is from the tunnel portal to +10m of the shield main machine, the quincunx holes are constructed in I-order holes and II-order holes with a hole distance of 1.5m×1.5m, and there are 800 quincunx holes, 400 holes are arranged in I-order holes 1 first, and then 400 holes are arranged in II-order holes 2.

[0031] The grouting process of step S3 adopts segmented construction, and grouting is performed from bottom to top every 1m; The grouting pipe structure of step S3 adopts a one-way valve pipe with a diameter of 40-60mm, and 2-3 groups of jetting holes are arranged per meter of the one-way valve pipe; The slurry of step S3 adopts a fast-setting multi-component slurry, wherein the initial setting is <60min, the 4h strength is ≥220MPa, the 28d strength is ≥30MPa, k is ≤10×-8 cm / s, and the fluidity is ≤18s.

[0032] The water-cement ratio is changed by four-stage gradual thickening, and the water-cement ratios are 2:1, 1:1, 0.8:1, and 0.5:1 in sequence; In step S3, the inspection holes for quality inspection are not less than 5%, and a 1.2Mpa water pressure test is performed 3 days after grouting, wherein the water permeability of not less than 85% of the hole sections is not greater than 3Lu; In step S3, the hole sealing process adopts thick slurry with a water-cement ratio of 0.5:1, and pure pressure sealing is performed at 0.5Mpa.

[0033] The end standard of step S3 is that the injection rate is ≤1L / min at 1.5MPa for 30min (average ≤1.0L / min).

[0034] S4: Dynamic control of shield launching; In step S4, the diameter of the shield machine is not less than 12m, the launching depth is not less than 60m, the soil chamber pressure is 1.05-1.1 times the water-soil pressure, the rotation speed is not greater than 0.8rpm, and the speed is not greater than 5mm / min; the shield machine adopts quick-setting double-liquid slurry for synchronous grouting, and polyurethane is used for gap sealing after the shield tail is removed S5: Whole-process monitoring and early warning, the monitoring items of step S5 include well water level, well water pressure, cord pressing force, ground settlement, and seepage flow, and emergency grouting is started when the water inflow suddenly increases by more than 10% or the settlement is greater than 5mm / 24h.

[0035] Through the above method, the fissure water depth is blocked: the Meihua hole + splitting penetration grouting makes the water permeability ≤3Lu, overcoming the problem of uneven penetration in traditional process; fast setting and high efficiency: 4h strength ≥20MPa, slurry shortens the construction period by >30%; three waterproof safeguards: deep grouting body (main waterproof) + hole sealing (emergency water blocking) + synchronous grouting (secondary sealing); through linkage alarm intelligent control, the parameters are dynamically adjusted based on real-time monitoring.

[0036] The foregoing is considered as illustrative only of the principles of the application. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the application to the exact construction and operation described. Accordingly, all such variations are intended to be included within the scope of the present application as defined in the claims below and their equivalents.

Claims

1. A method for large-diameter earth pressure balance shield tunneling to initiate water interception and control in ultra-deep water-rich soft rock strata, characterized in that: Includes the following steps: S1: Refined geological and hydrological modeling; S2: The starting tunnel portal adopts a multi-stage composite sealing system; S3: Precision grouting reinforcement is applied to deep fissures. Step S3 includes reinforcement range, hole layout method, grouting process, grouting pipe structure, grout, quality inspection and hole sealing process. S4: Dynamic control of shield tunneling initiation; S5: Full-process monitoring and early warning; emergency grouting will be initiated when the water inflow suddenly increases by more than 10% or the settlement is greater than 5mm / 24h.

2. The method for large-diameter earth pressure balance shield tunneling to initiate water interception and control in ultra-deep water-rich soft rock strata according to claim 1, characterized in that: The reinforcement range described in step S3 is 10m above and below the shield tunneling range, and D meters outside the outer diameter D of the tunnel. The reinforcement length is +10m of the shield machine. The hole layout method described in step S3 adopts a quincunx pattern with a hole spacing of 1.5m × 1.5m, and the construction is carried out using sequence I holes to sequence II holes; The grouting process described in step S3 adopts segmented construction, with grouting every 1m from bottom to top; The grouting pipe structure described in step S3 adopts a one-way valve pipe with a diameter of 40-60mm, and the one-way valve pipe is provided with 2-3 sets of grout injection holes per meter; The slurry mentioned in step S3 is a fast-setting multi-component slurry, and the water-cement ratio is changed by four-stage progressive thickening, with water-cement ratios of 2:1, 1:1, 0.8:1, and 0.5:1 respectively. In step S3, the number of inspection holes for quality inspection shall not be less than 5%. A 1.2 MPa water pressure test shall be conducted 3 days after grouting, and the permeability of not less than 85% of the hole sections shall not exceed 3 Lu. In step S3, the sealing process uses a concentrated slurry with a water-cement ratio of 0.5:1, and a pure pressure sealing method with a pressure of 0.5 MPa is used.

3. The method for large-diameter earth pressure balance shield tunneling to initiate water interception and control in ultra-deep water-rich soft rock strata according to claim 1, characterized in that: Step S1 includes the following sub-steps: S11: Through TSP, borehole television and pumping tests, determine the location, width and water conductivity of the crack distribution within a range of +20m of the shield tunnel length; S12: Establish a three-dimensional hydrogeological model to predict water inflow channels.

4. The method for large-diameter earth pressure balance shield tunneling to initiate water interception and control in ultra-deep water-rich soft rock strata according to claim 1, characterized in that: Step S2 includes the following sub-steps: S21: Pre-embedded double-channel grouting pipe steel ring, wherein the pressure bearing capacity of the grouting pipe steel ring is not less than 1.5 times the hydrostatic pressure; S22: A circumferential deep-hole grouting curtain is installed outside the tunnel portal; S23: The portal is equipped with a special sealing curtain and a triple hydraulic pressure plate. The special sealing curtain is made of polyurethane curtain reinforced with two layers of aramid fiber, and the pressure resistance of the special sealing curtain is not less than 1.0 MPa.

5. The method for large-diameter earth pressure balance shield tunneling to initiate water interception and control in ultra-deep water-rich soft rock strata according to claim 1, characterized in that: Step S22 includes: installing three rows of sleeve valve pipes circumferentially outside the portal, wherein the depth of the buried hole of the sleeve valve pipe is not less than 5m from the water-stop layer, and injecting ultrafine cement-water glass slurry solution into the sleeve valve pipe to form a water-stop body with a permeability k<10×-7cm / s.

6. The method for large-diameter earth pressure balance shield tunneling to initiate water interception and control in ultra-deep water-rich soft rock strata according to claim 1, characterized in that: In step S4, the diameter of the tunnel boring machine (TBM) shall not be less than 12m, the starting depth shall not be less than 60m, the soil chamber pressure shall be 1.05-1.1 times the soil and water pressure, the rotation speed shall not be greater than 0.8rpm, and the speed shall not be greater than 5mm / min. The synchronous grouting of the TBM shall use fast-setting dual-liquid grout, and the secondary grouting shall be performed by sealing the gap with polyurethane after the shield tail has exited.

7. The method for large-diameter earth pressure balance shield tunneling to initiate water interception and control in ultra-deep water-rich soft rock strata according to claim 1, characterized in that: The monitoring items in step S5 include well water level, well water pressure, curtain tension, surface settlement, and seepage flow.

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